JPH05189590A - Wand type reading apparatus - Google Patents

Abstract

PURPOSE: To easily read bar codes having various densities by operation angles in a wide range. CONSTITUTION: Light emitting elements 61 and 62, a photodetection element 63, and a related circuit network are so arranged that two data channels are obtained from a scanned bar code. Two channels have different resolutions. Data of two channels are analyzed to obtain one decoded result. Though the operation angle and the density of the bar code are changed, at least one of two channels having different resolutions must be suitable for detection of the whole or most of bar code data. Data of the channel which generates the correct result can be used as it is. Even if two channels don't generate correct results by themselves, data of each channel is analyzed, and correct parts of their data are combined to generate one correct decoded result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved wand reader for reading optically coded information, particularly bar codes.

[0002]

Bar code or optically encoded information has become commonplace. The bar code symbol is
Generally, it consists of a series of rectangular light areas (spaces) and dark areas (bars). The width of the bars and / or the width of the space between the bars represent the encoded information, and the specified number and array of these elements represent the characters. The standardized code system is
It specifies the array for each character, the allowable width and spacing of elements, the number of characters that a symbol can contain, whether the length of the symbol can be changed, and so on.

In order to decode the bar code symbol and retrieve the correct message, the bar code reader scans the symbol and produces an analog electrical signal representative of the scanned symbol. Various types of readers are known, but a wand reader in which a light emitting element and a detector are fixedly installed in the wand may be used. In this case, the user manually moves the wand along the symbol. In another reader, an optical scanner scans a light beam, such as a laser beam, across the symbol and a photodetector detects the light reflected from the symbol. In either case, the photodetector senses the light reflected from the spot scanned across the symbol and produces an analog scan signal representative of the encoded information.

The digitizer processes the analog scan signal to generate a pulse signal. The width of the pulse and the spacing between the pulses correspond to the width of the bars and the spacing between the bars. The digitizer functions as an edge detector or waveform shaping circuit, and the threshold set by the digitizer determines which point in the analog signal represents the edge of the bar. The threshold level effectively defines the portion of the signal that the reader perceives as a bar or space.

A reader of the above type is a single channel system with one processing chain producing one digitizer output and / or one digitized output.

The pulse signal from the digitizer is applied to the decoder. The decoder first measures the pulse width and spacing of the signal from the digitizer. The decoder then analyzes the pulse width and spacing to find and decode the correct bar code message. This process involves analysis to recognize the correct characters and order defined in the appropriate code standard. The process further includes first identifying the particular standard with which the scanned symbol complies. This conforming standard identification is commonly referred to as "automatic identification."

Different barcodes have different information densities and contain different numbers of elements representing different amounts of coded data within a given area. The higher the bar code density, the narrower the bar elements and their spacing. Printing high density symbols on a suitable medium is cumbersome and therefore more expensive than printing low density symbols.

Bar code readers generally have a specified resolution and are often represented by the size of the effective detection spot. The resolution of the reader depends on the parameters of the light emitting element or photodetector, the lens or aperture coupled to either the light emitting element or photodetector, the threshold level of the digitizer, the programming in the decoder, or of these elements. Determined by a combination of two or more.

In the case of a laser beam scanner, the effective detection spot may coincide with the beam size at the point where the light beam hits the bar code. In the case of wands using LEDs or the like, the size of the effective detection spot may be the illuminated area, or the portion of the illuminated area where the photodetector effectively detects the reflection of light. Whatever means the spot size of a particular reader is set, the photodetector effectively averages the light detected over the area of the detection spot.

As an example of the prior art, US Pat. No. 4,675,
In the device described in 531, an LED illuminates a bar code and the bar code is imaged on a photodetector. The resolution or "spot size" is determined by the aperture of the photodetector. Also in this device, the photodetector effectively averages the light detected over the area of the aperture.

High resolution readers can decode high density symbols because of their small spot size,
Due to the poor print quality used for low density symbols, accurate reading of low density symbols is difficult. This is true especially for symbols printed by the dot matrix method. High resolution readers may actually detect the width of the dots within the bar as individual bar elements. In contrast, low resolution readers have a large spot size, which allows them to decode low density symbols. But,
Since readers for relatively noisy symbols, such as dot matrix barcodes, read wide spots, there may be two or more dense bars of dense symbols in the spot at the same time. Therefore, a low resolution reader suitable for a dot matrix barcode cannot accurately read a high density symbol. Therefore, any fixed resolution reader can only read barcodes with a limited range of symbol density.

Also, if the symbol density is constant, the resolution of the reader limits the range of working angles (the angle between the axis of the reader and the line perpendicular to the surface on which the bar code is printed). If the working angle range is too limited, the user may struggle to comfortably hold the reader, especially the wand reader, while accurately scanning the bar code. This is a particularly daunting task if the components that make up the integrated data terminal are additionally integrated into the wand. The size, weight, and tight working angle can make reading large amounts of bar code information difficult and irritating, and the user may be reluctant to use the bar code system.

One solution is to provide some means of adjusting the resolution of the reader, ie the detected spot size, for example by adjusting the threshold of the digitizer. However, this method would require multiple separate scans at different resolutions. If the scan is automatic, the change in resolution causes a reduction in the robustness of the device, since the scan is at the correct resolution for a short time. In effect, such a device would scan at a low equivalent speed. If the reader is a wand, then the user must manually scan the wand across the information each time the resolution changes. this is,
Since the first reading rate is significantly reduced, the user is irritated.

From the above, it is clear that there is a need in this field for a high performance bar code reader capable of operating over a wide range of working angles and capable of reading bar codes over a wide range of symbol densities. Is.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention, especially for use by relatively unskilled operators,
And to provide an efficient and high performance bar code reader.

A more specific object of the invention is to obtain large amounts of information from each scan by a single bar code scanner or reader.

In particular, the object of the present invention is to use the additional information obtained in a single scan to cover a wide range of working angles (the angle between the line perpendicular to the surface on which the bar code is printed and the wand).
And obtaining accurate readings with the wand over a wide range of distances from the wand to the printed bar code. A wide working angle range allows even an inexperienced operator to scan the bar code at the most convenient and comfortable angle and still have a high percentage of successful first readings. Process scanned bar code data and data entered with the built-in keyboard, save,
This feature, i.e. ease of operation, is particularly important when the additional elements that make up the integrated terminal device for display are incorporated into the wand reader.

Another object of the invention is to read a wide range of density bar codes with the additional information obtained from a single scan without having to scan the information multiple times. This allows two or more readers conventionally required (each reader is necessarily designed to read barcodes in a limited range of densities) with one improved reader. It can be replaced. For relatively unskilled users, this eliminates the above-mentioned problems and the annoyance of choosing a reader or adjusting the sensitivity of the reader to suit the density of the particular bar code being scanned. To do.

[0019]

SUMMARY OF THE INVENTION To operate over a wide range of working angles, the present invention uses two effective detection spots of different diameters to optically encode information (ie, a bar code).
To detect. When the working angle changes, one of the two spots will be in good focus and a correct reading will be obtained. If none of the spots are in focus, the information from the two spots can often be combined to accurately decode the information.

For reading a wide range of density bar codes, the reader is equipped with two read channels,
One correct decoding result is obtained from the scan data of the two channels. In general, one channel will have a resolution that matches the density of the currently scanned barcode. However, if not, it is possible to combine the correct parts of the data from each channel to get one accurate decoding result.

As a first aspect, the present invention provides a method for expanding the working angle range of a wand type reader when reading optically encoded information. The working angle is the angle between the principal axis of the wand reader and a line perpendicular to the surface on which the optically encoded information is printed. The method includes arranging a light emitting element and a detection element, (i) optically detecting light reflected from a first effective detection spot of a first diameter, and (ii) a second diameter larger than the first diameter. Optically detecting the light reflected from the second effective detection spot. The first and second valid detection spots pass over the optically encoded information. Thereby, (i) when the first effective detection spot passes the optically encoded information, the optically encoded information is detected to generate the first detection signal, and (ii) the second effective detection spot is optically encoded. The optically encoded information is detected as it passes through the encoded information to generate a second detection signal. The diameters of the first and second effective detection spots increase in proportion to the increase in working angle. The method further comprises the step of obtaining a decoded representation of the optical encoded information from the two detected signals. At different working angles, the at least one effective detection spot will have a suitable size such that the optical coded information can be correctly read.

The invention, in a second aspect, provides an apparatus corresponding to the method described above. More specifically, the device is a wand reader that reads optically encoded information over a wide range of working angles. The wand type reader has a light emitting element and a detection element arranged in the wand,
When the first effective detection spot of the first diameter passes over the optically encoded information, the light reflected from the first effective detection spot is optically detected and the corresponding first detection signal is generated. Further, the light emitting element and the detection element optically detect the light reflected from the second effective detection spot when the second effective detection spot having the second diameter larger than the first diameter passes over the optically encoded information. However, it is arranged so as to generate a second detection signal corresponding thereto. The diameters of the first and second effective detection spots increase in proportion to the increase in working angle. The wand reader further comprises means for deriving a decoded representation of the optically encoded information from the two detected signals. As a result, for various working angles, at least one valid detection spot will have an appropriate size that will result in a correct reading of the optically encoded information.

As a third aspect, the present invention provides a method for reading optically encoded information. The method optically exposes the optically encoded information and detects light reflected from the optically encoded information to detect two data streams, each data stream being associated with the optically encoded information. Including the step of generating The two data streams have different resolutions. The method obtains a decoded representation of the optical coded information from the two data streams.

As a fourth aspect, the present invention provides an apparatus for reading optically encoded information. The device comprises detection means, ie at least one detector for optically detecting the encoded information and generating at least one electrical signal corresponding thereto. The apparatus further comprises means for directing two data streams in response to at least one electrical signal for each scan of the optically encoded information by the detector. The two data streams likewise have different resolutions. The decoder produces, in response to the two data streams, one data output representing the detected optically encoded information.

As a fifth aspect, the present invention provides an improved optical detection device. The optical detection device has first and second light emitting elements that emit light along the first and second optical axes, and a light detection element that detects reflected light from the first and second light emitting elements. The photodetector element receives light reflected along a third optical axis parallel to the first and second optical axes. The optical detection device further has a spherical boundary surface at the rear,
And a first and second half axicon optical element aligned with the light emitting element along the second optical axis. The first half axicon optical element determines the depth of field and the spot size of the light emitted by the first light emitting element and received by the photodetecting element. Similarly, the second half axicon optical element determines the depth of field and the spot size of the light emitted by the second light emitting element and received by the photodetecting element. The two half axicon optical elements may be the same or different. If the two half axicon optics are identical, one spot size that is fairly symmetrical with one depth of field is obtained. If different, each half-axicon optical element defines a different depth of field and spot size.

As a sixth aspect, the present invention provides an improved photodetector. The photodetector of the present invention is a multichannel photodetector in which two active photodetection areas are formed on one substrate. The second light detection area is arranged around the first light detection area.

The present invention includes many systems which provide two data channels with different resolutions and / or two detection spots. For example, in the simplest embodiment, the wand reader has an LED light source and a single photodiode type detector. The detector signal passes through two different signal conditioning circuits and associated digitizers. One signal conditioning circuit and associated digitizer produces a high resolution output and the other signal conditioning circuit and associated digitizer produces a low resolution output. 2 microprocessors
The digital data from one channel is analyzed and the scanned barcode data is decoded. The two resolution channels allow the scanning of both dense high resolution barcodes and low resolution barcodes (eg, barcodes printed by dot matrix printers) in a single scan with a single barcode reader. ..

It is also possible to use one light source and two detectors. The characteristics of the two detectors and / or their associated optics are different in order to obtain the two different resolutions required. In one particularly useful embodiment, 2
Each of the two detectors is a photodiode and the two photodiodes are made as a single concentric structure. That is, the first photodiode is formed in the center and the second photodiode is formed around it. The first analog-to-digital converter digitizes the signal output from the first photodiode to create a high resolution data channel. The signal output of the first photodiode and the signal output of the second photodiode are then summed. A second analog-to-digital converter digitizes the summed signal to create a low resolution data channel.

Yet another method is to install two different light emitting elements and two detectors. Each pair of light emitting elements / detectors provides one channel of scanning information. The resolution of each channel is determined by one or more optical components, namely the structure of the light emitting element, the structure of the detector, or the aperture coupled to a pair of light emitting elements / detectors.

Whatever system is used to obtain the two channels, the microprocessor analyzes the data from each channel to identify which one yields the correct decoding result, and the resulting data from that channel. Can be selected as output data. Channels with resolutions that are inconsistent with the density of the bar code currently being read will cause noticeable read errors.

Alternatively, the microprocessor can merge the data from the two channels to produce one correct result, even if neither of the two individual channels produces a correct read. The microprocessor identifies which portion of the data read from each channel is within acceptable parameters for a read operation of matching resolution. The microprocessor discards any data from the two channels that appear out of tolerance. The microprocessor combines the acceptable parts of the data from the two channels,
Produces one correct final read result.

A high performance wand bar code reader should have the following features: -Built-in decoder, -Automatic identification of the most widely used symbology, -Wide resolution range (from low density bar code to high density bar code, ie 5-20 mils, well printed bar code to dot. Matrix barcodes), easy reading on plastic or lamination,

If the light emitting element / detector module has a high depth of field and a variable spot size, the above technical requirements can be met. For example, typically 2 mm for reading on plastic or lamination
Depth of field is required and a spot size of 0.5 mm is required to read dot matrix barcodes.

The objects, advantages and novel features of the present invention other than the above are mentioned in part in the following description.
It will be apparent from a careful reading of the following description, and will be understood by practicing the invention.

[0035]

1 and 2 illustrate bar code scanning and how the present invention works to extend the range of working angle .theta. For a wand reader. FIG. 1 shows a wand reader 10 (hereinafter sometimes simply referred to as a wand) being manually scanned across a bar code 20.
As shown, the working angle θ is defined as the angle formed by a line perpendicular to the surface on which the optical coded information is placed and the main axis of the wand 10. The working angle θ of the wand 10 shown in FIG. 1 is about 45 °.
2 corresponds to b in FIG. However, the wand 10 can be held in a wide range of angles, for example in a 0 ° position (corresponding to c in FIG. 1).

The light emitting element and the detection element of the wand 10 are arranged so that _two effective detection spots S ₁ and S ₂ having different diameters are generated. FIG. 2 shows that the two detection spots S ₁ and S ₂ have different diameters and shapes for different working angles θ. In the 0 ° attitude, two detection spots S
₁ and S ₂ are necessarily concentric circles. However, as the angle θ increases to a, b, and c, the two detection spots S ₁ ,
S ₂ gradually loses its shape and expands into a large ellipse.

If the reader is a wand reader, the user manually moves the wand to scan two detection spots across the bar code. By this scan,
(I) When the first effective detection spot passes the optical encoded information, the optical encoded information is detected to generate the first detection signal, and (ii) the second effective detection spot outputs the optical encoded information. As it passes, the optically encoded information is detected and a second detection signal is generated.

In scanning a bar code or other optically encoded information, first and second detection spots S ₁ , S
₂ is scanned across the optical encoded information. Figure 3
Indicates scanning of the detection spots S ₁ and S ₂ across the barcode 20 for a relatively small working angle θ. The user
Since the working angle θ is maintained at 0 ° or an angle close to 0 ° from end to end of the scanning length, the detection spots S ₁ and S ₂ inevitably remain circular.

If the user changes the working angle, the sizes and shapes of the detection spots S ₁ and S ₂ change as shown in FIG. The diameters of the first and second effective detection spots S ₁ and S ₂ increase in proportion to the increase in working angle. The present invention provides two detection spots S ₁ and S ₁ across the optical coded information.
_{From the two} detection signals obtained by scanning ₂ , the decoded representation of one optical encoded information is obtained. At various working angles, at least one valid detection spot will be of proper size and will produce a correct reading of the optically encoded information.

For relatively low density bar codes, a working angle of 0 ° can give a large circular detection spot S ₁ as shown in FIG. 2a. However, for some noisy printed barcodes, such as dot matrix printed barcodes, the small diameter sensing spot S ₂ is actually too small. At a slightly larger angle, for example b in FIG. 2, the two detection spots S ₁ and S ₂ are
At least some readable information can be provided. The two pieces of information can later be merged to obtain one correct decoding result. When working angle θ increases, the spot S _1, S ₂ becomes elongated, while the spots S ₁ of larger diameter at many angles too large, the spot S ₂ of the smaller diameter will have an appropriate diameter.

FIG. 3 shows the scanning of spots S ₁ and S ₂ across a relatively dense bar code 20. Working angle is 0 °
Or, since it is close to it, the spots S ₁ and S ₂ are necessarily circular. At some point during the scanning of the high density bar code, particularly at the two central locations, the area of the large diameter spot S ₁ spans two or more bar elements. Averaging such areas would not give an accurate signal indicating the edges of narrow bar elements. In contrast, the small-diameter spot S ₂ has a narrow range, and even at the above-mentioned position it covers only one narrow bar element.

FIG. 4 shows the scanning of spots S ₁ , S ₂ across one bar element 23 of a dot matrix bar code. As shown, in practice there are gaps in the individual dods of the bar element 23. Detection using a small diameter spot S ₂ will detect dots as dark areas and gaps as bright areas. For example, at the position shown in FIG. 4, the small diameter spot S ₂ substantially coincides with one of the gaps. As a result, the signal corresponding to the detection of spot S ₂ will point to a bright space rather than a dark bar at that point. Therefore, detection using spot S ₂ will not accurately read the width of bar element 23. On the other hand, a large diameter spot S ₁ will give correct decoding results. Detection using spot S ₁ will average the reflected light over a large area of that spot and will indicate a dark bar.

FIG. 5 shows a first embodiment of the invention, the simplest way to generate two channels with two different resolutions or detection spots. This example
A digitizer with different resolutions is used to electronically obtain two different resolutions. The reader may be an automatic scanner or a wand reader that requires manual scanning. The circuitry of FIG. 5 will now be described, assuming the reader is a wand type.

The embodiment of FIG. 5 has a single light source or light emitting diode (LED) 41 and a single photodetector or photodiode (PD) 42. The LED 41 emits light to illuminate an area on the surface of the optical coded information (bar code) 20. The PD 42 senses the light reflected from the barcode 20 and generates an analog signal. The amplitude of the analog signal represents the amplitude of reflected light. The reader scans the bar code. If the reader is a wand type device, the user manually moves the wand across the bar code.
The amplitude of the analog signal corresponding to the sensed reflected light changes depending on the light area and the dark area of the barcode.

The analog signal from the PD 42 is amplified, inverted and adjusted by the two analog signal adjusting circuits 43 and 44. The signal conditioning circuits 43, 44 are essentially identical and thus provide two analog output signals. One of these output signals is the first digitizer 45.
And the other one is sent to the second digitizer 46. Digitizers 45 and 46 are similar to the digitizers used in conventional single channel readers.
It acts as an edge detector or waveform shaping circuit. In each digitizer 45, 46, the digitizer defined threshold determines which point in the analog signal represents the edge of the bar. However, the digitizers 45 and 46 have different thresholds.

The pulse signals output from the two digitizers 45 and 46 are sent as inputs to a programmed microprocessor type decoder 47. Signal conditioning circuit 4
3 and the digitizer 45 form a first channel which provides a first data stream to the decoder 47. The signal conditioning circuit 44 and the digitizer 46 form a second channel that provides a second data stream to the decoder 47. Since the threshold value T ₁ of the _first digitizer 43 is set relatively low as shown in FIGS. 6 and 7, the digitizer 43 has a low resolution. On the other hand, the second digitizer 46 has a high threshold value T _{2 and} high sensitivity.

FIG. 6 shows a high resolution bar code and the signals produced in the circuit of FIG. 5 by scanning the bar code. The analog signal will fluctuate by averaging the reflected light and, after being adjusted, will have small fluctuations corresponding to closely spaced bars. First digitizer 4 for channel 1
Due to the low threshold of 5, some of the variations will not be detected, as shown by the pulsed signal from digitizer 45 in FIG. The high resolution second channel will detect small variations in reflected light caused by closely spaced bar elements, as the sensitive digitizer 46 will also pick up small bumps in the analog signal. Therefore, the high resolution second channel will output a pulse train from the digitizer 46 that exactly matches the edge of the barcode, as shown in FIG.

FIG. 7 shows a dot matrix low resolution bar code and signals generated in the circuit of FIG. 5 by scanning the bar code. The analog signal will fluctuate by averaging the reflected light and, after being adjusted, will have small fluctuations corresponding to the dots of the matrix. The analog signal will also have large variations corresponding to the actual elements of the bar code symbol. Due to the low threshold of the first digitizer 45, small variations in the analog signal will not be detected, as shown by the pulse signal from the digitizer 45 in FIG. Therefore, the low resolution first channel will output a pulse train from the digitizer 45 that exactly matches the edge of the barcode. In contrast, the high resolution second channel will detect small variations in the reflected light caused by the interstitial dots in the bar element as the sensitive digitizer 46 picks up small ridges in the analog signal. Let's do it. Therefore, the pulse signal from the digitizer 46 will not coincide with the actual edge of the bar element, as shown in FIG.

From FIGS. 6 and 7, for both high resolution and low resolution barcodes, one of the two channels has a pulse signal output or data that exactly matches the edge of the scanned barcode. It will be obvious to create a stream. Decoder 47
Is a relatively standard unit except that it has two inputs instead of one for two data streams of two different resolution channels. The integrated decoder 47 provides a digital data output, for example in ASCII format. The special decoding operation will be described later in detail with reference to FIGS. 19 and 20.

The above two data channels can be obtained using various methods. Many of the more sophisticated alternatives are shown in the figures below FIG. However, in each embodiment, the device uses two channels from two different resolutions.
One data stream is provided to one decoder 47. The decoder 47 is the same.

The embodiment of FIG. 8 optically produces two different channels. This embodiment has two light emitting devices and two light emitting devices.
Equipped with individual detectors. The first LED 51 emits light,
The first spot on the barcode 20 is illuminated. LED5
The light emitted from 1 is reflected by the barcode and returns to the 1st P
Detected by D52. The first signal conditioning circuit 53 and the first digitizer 54 output the low resolution data stream as a pulse train signal to the decoder 47. Second LED 55
Emits light to illuminate a second spot on the barcode 20. The light emitted from the LED 55 is reflected by the barcode, returns, and is detected by the second PD 56. The second signal conditioning circuit 57 and the second digitizer 58 output the low resolution data stream as a pulse train signal to the decoder 47.

As shown in FIG. 8, the light emitting element and the detector are
The two spots are arranged so that they are placed slightly apart. This is called spatial multiplexing. Other types of multiplexing can be used if the two spots are to be concentric. For example, the PDs 52 and 56 may be designed so that the LEDs 51 and 55 emit lights of different wavelengths and only the lights from the corresponding LEDs are detected, or an optical filter may be provided.

LED 51, PD 52, signal adjusting circuit 5
3, and digitizer 54 constitutes the low resolution channel. LED55, PD56, signal adjustment circuit 57,
And the digitizer 58 constitutes the high resolution channel. In this embodiment, the resolution and spot size of each channel is determined by the characteristics of the LED, PD, associated optics or apertures associated therewith. For example, the optical device can focus the light from each LED to produce different sized illumination spots at different distances from the wand tip. Alternatively to the above, it is possible to obtain different areas (on which the reflected light is averaged) by varying the size of the PDs, ie each PD having a different aperture. The thresholds of the digitizers 54 and 58 may be the same, but it is preferable to set the thresholds of the digitizers 54 and 58 so as to correspond to the characteristics of the LEDs, PDs, and optical devices of the corresponding channels.

The embodiment of FIG. 9 uses two light emitting elements and one detector. To generate two channels,
The detector output is multiplexed synchronously with the pulsing of the individual emitters. The two light emitting elements and / or the associated optics are different in order to obtain two different effective detection spots and two different resolutions. The two spots can be closely aligned, ie, substantially concentric on the surface with the barcode 20. The high resolution and low resolution signals are time division multiplexed by pulsing the individual LEDs.

In this third embodiment, two LEDs 61,
62 and one PD 63. Multiplexer 64
Alternately activates the LEDs 61 and 62. The multiplexer 65 also includes two extraction / holding (S / H) circuits 6
The output of PD63 is given to one of 6,67. The signal conditioning circuit 68 and the digitizer 70 provide the pulse signal of the low resolution channel to the decoder 47. Further, the signal adjusting circuit 69 and the digitizer 71 give the pulse signal of the high resolution channel to the decoder 47. Clock 72 provides the appropriate timing signals to multiplexers 64 and 65 and S / H.
It is given to the circuits 66 and 67. It is also possible to multiplex by rapidly pulsing two LEDs at two different frequencies and performing frequency decoding.

The LED 61 and its associated optics are designed to provide a relatively large illumination spot, and the LED 6
2 and its associated optics are designed to provide a relatively small illumination spot. The signal from the clock 72 is
The multiplexer 64 is driven to trigger the LED 61, and the multiplexer 65 is driven to drive the PD 63 to the S
A signal is applied to the / H circuit 66. The S / H circuit 66 is LE
Hold a sample of the low resolution analog signal produced by D61 and PD63. The signal from the clock 72 then drives the multiplexer 64 to trigger the LED 62 and the multiplexer 65 to provide a signal from the PD 63 to the S / H circuit 67. The S / H circuit 67 is
Holds a sample of the high resolution analog signal produced by LED 62 and PD 63. This cycle repeats so that the S / H circuits 66 and 67 continuously hold samples of two different resolution analog signals.

Next, the signal conditioning circuit and the digitizer are
The data streams of three different resolutions are provided to the decoder 47. Signal conditioning circuits 68, 69 and digitizer 7
0 and 71 correspond exactly to the signal conditioning circuit and digitizer of the previous embodiment.

FIGS. 10-14 show a preferred embodiment of the optics of an improved reader (configured in wand form). As shown in FIGS. 10 to 14, the optical device of the two-channel wand type reading device creates a three-axis anamorphic optical system configured by combining two half axicons. In this design, two LEDs and one detector are used, and the LEDs operate alternately, as in the network embodiment of FIG.

The optical device shown in FIGS. 10 to 14, that is, the optical detection device has a first LED 61 and a second LED 62. These two light emitting elements are arranged in the device housing 75 so as to emit light along the first and second optical axes, respectively. That is, as shown in FIG.
D61 emits light along axis 1 and LED 62 emits light along axis 2
Emit light along. The photo detector PD63 has two LEDs
The light emitted from 61 and 62 and reflected by the barcode is detected. The PD 63 is arranged in the sleeve 79 so as to receive the reflected light along the central axis of the optical detection device, that is, the axis 3. Axis 3 is parallel to the first and second optical axes (ie axis 1 and axis 2). The optical detection device further includes an injection molded plastic optical element 77.
Have. The optical element 77 is composed of first and second half axicon labeled as axicon 1 and axicon 2 in FIG. Axicon 1 LED along axis 1
61 is aligned, and the axicon 2 is aligned with the LED 62 along the axis 2.

The first half-axicon optical element, that is, the axicon 1, determines the depth of field and the spot size of the light emitted by the LED 61 and received by the PD 63. Similarly, the axicon 2 determines the depth of field and the spot size for the light emitted by the LED 62 and received by the PD 63. However, the two half axicons may be separate so that each half axicon defines a different depth of field and spot size, giving the two channels two different resolutions.

Each half-axicon has a rear surface that is a spherical surface and a front surface that is made with a specified assicicon angle α. Axicon 1 has a rear surface SA1 that focuses on F1
(FIG. 14). Axicon 2 has a posterior surface SA2 of curvature that focuses on F2 (FIG. 14). Each LED 61,
The reference numeral 62 is arranged at the focal points F1 and F2.

As shown in FIG. 10, the axicon angle of each half axicon is defined as the angle formed by the front surface of the half axicon and a line perpendicular to the three axes of the optical system. The axicon angles of axicon 1 and axicon 2 are different (α ₁ ≠ α ₂ ) to give different depths of field and spot sizes.
The light diverted from the LEDs 61 and 62 to the side is the axicon 1
Is refracted by the axicon 2 into parallel rays, which are collected on the barcode (FIG. 14).

Further, a sleeve 79 extending from the rear wall of the housing to the front of the PD 63 is arranged in the housing 75. The sleeve 79 has a function of preventing the light emitted from the LEDs 61 and 62 and reflected by the rear surfaces SA1 and SA2 from hitting the PD 63 so as not to interfere with the detection of the reflected light from the barcode. The sleeve 79 is concentric with the axis 3 (Fig. 12). Also, on the rear wall of the housing 75, LE
A large number of holes for passing lead wires from D61, 62 and PD63 are provided (FIG. 13).

As shown in FIG. 21, an alternative lens array for a 2-channel wand head has two LEDs 51, 5
Five and two photodetectors 52,56 could be used. In that case, the optical detector of FIG. 21 would be used in the circuitry of FIG. 2 LEDs 5
The light from 1,55 is focused on the same target by the _two aspherical lenses L ₁ , L ₂ . The light reflected from the target is collected on the photodetectors 52 and 56 by the lenses L ₃ and L ₄ and converted into an analog electric signal. Lens L
The difference between ₁ and L ₂ is their spherical aberration. Spherical aberration is used to control light intensity, depth of field, and surface illumination range.

As shown in FIG. 23, the spherical aberration is an aberration whose focal length differs depending on the height of the incident light beam. F is the focal point of the paraxial ray and F _m is the point where the marginal ray intersects the optical axis. The distance connecting these two points is the longitudinal spherical aberration L.L. It is SA. This spherical aberration has the effect of increasing the depth of field. The image stretches horizontally. The radius of this image depends on the lateral spherical aberration T.I. It is called SA and is represented by the following equation.

T. SA = L. SA x tanU

The lens L ₁ has an L. SA and about 5
Mill T. SA with a lens L ₂ of about 2 mm L.S. S
A and 20 mil T.S. Have SA. Therefore, the radii of the transparent apertures of the two lenses are different to obtain different values of the angle U in the above equation.

FIG. 15 is a schematic plan view of a photodetector having two active areas # 1 and # 2. As shown, a mesh-shaped shaded central circular active area # 1 surrounds a shaded shaded active area # 2. The structure of the photodetector of this embodiment will be described later with reference to FIGS. 17 and 18. A salient feature of this photodetector is that it essentially constitutes a multichannel detector. This multi-channel photodetector has a first active photodetection area on a substrate and a second active photodetection area made on the same substrate. The second light detection area is arranged around the first light detection area. Each active photodetection area, together with the underlying substrate, constitutes a photodiode. This photodetector is used in the embodiment of the present invention shown in FIG.

In the circuit of FIG. 16, the signal conditioning circuit and digitizer function similarly to the signal conditioning circuit and digitizer of the embodiments of FIGS. 8 and 9. The only difference is Figure 1
6 shows a high resolution channel with a second digitizer as the upper channel and a first digitizer as the lower channel.

In this embodiment, there is one light emitting element and two photodetectors, the photodetectors comprising the active detection area of the device shown in FIG. In FIG. 16, D1 represents a photodetector having active area # 1 (central active area),
D2 represents a photodetector with active area # 2 (surrounding active area). The LED 131 emits light that illuminates the optically encoded information. The photodetectors D1 and D2 receive the light reflected from the surface of the barcode 20.

The photodetector D1 produces an analog signal that represents the average of the light reflected from across the small active area # 1 which is actually small. This signal is the same as when using a small effective detection area photodiode, which determines the spot size and / or the resolution of the high resolution channel.

The photodetector D2 produces an analog signal which represents the average of the light reflected from all over the active area # 2, which is actually large. The analog signals from D1 and D2 are summed by adder 132. This sum of the analog signals is very close to the signal produced by averaging the light reflected from the larger photodiode, ie, the total active area plus area # 1 and area # 2.

The signal conditioning circuit 133 receives the summed signal from the adder 132 and conditions it as described above. The signal from the signal conditioning circuit 133 is digitized by the first digitizer 134 to produce a low resolution data stream. Therefore, the detectors D1 and D2, the adder 132,
Signal conditioning circuit 133 and first digitizer 134
, Which constitutes the low-resolution first channel of this embodiment.
On the other hand, the signal conditioning circuit 137 receives the signal from D1,
Adjust as above. The signal from the signal conditioning circuit 137 is digitized by the second digitizer 138,
A high resolution data stream is created. Therefore,
The detector D1, the signal conditioning circuit 137, and the second digitizer 138 form the high-resolution first channel of this embodiment. The decoder 47 receives the pulse signals from the digitizers 134, 138 and processes them as in the previously described embodiment.

The photodetector of FIG. 15 is preferably used in the same type of optical detection device as shown in FIGS. In that case, the photodetector of FIG. 15 would be replaced by the PD63 of the optical detector and the LED 6 in the optical detector would appear as a single light source to the photodetector.
1, 62 are turned "on" at the same time. Axicon 1 and axicon 2 have the same axicon angle (α ₁ =
α ₂ ). Therefore, the size of the active area determines the resolution and spot size of the two channels.

By adding additional perimeter areas and corresponding adders, signal conditioning circuits, and digitizers,
It would be straightforward to increase the number of different resolution channels available using the photodetector of FIG. Alternatively to the above, two active areas could be used to pulsing the two LEDs in the optical detector, as in the circuit of FIG.

The photodetector of FIG. 15 is manufactured using relatively standard photodiode manufacturing techniques. In particular, the manufacturing process is similar to that used when manufacturing side-by-side photodiodes and quad-for-photodiode type devices. The size of the inactive area or dead zone between the active elements is generally 0.001 to 0.005. Possible layouts for the photodetector of FIG. 15 are shown in FIGS. 17 and 18.

In the first embodiment of FIG. 17, two active areas are created on the substrate 141. The first active area 142 is circular. The first active area 142 is created by suitable doping of the circular area. This active area 142
Is surrounded by a dead zone 143. The second active area 144 forms a substantially circular ring around the first active area 142 and the dead zone 143. The second active area 144 is made by suitable doping of a circular ring. Dead zone 143 has two active zones 1
42 and 144 are separated and electrically isolated. The common lead wire 148 is connected to the substrate 14 via the bonding pad 147.
It is attached to 1. Thus, each active area 142,
144 constitutes a photodiode with the substrate below.

FIG. 17 shows the preferred connection type for the first active area 142. In this embodiment, the second active area 144 does not form a complete ring around the first active area 142 and the narrow non-active area 149 has a second active area 144.
It forms an insulating passage across a ring made of.
Metal trace 14 formed on narrow inactive area 149
5 connects the first active area 142 to the bonding pad. In this way, current can be supplied to the first active area through the bonding pad and the metal trace 145. Similarly, metal trace 146 connects the second active area 144 to the bond pad. Inactive area 1
The width of the passage across the second active area 144 which is lost due to the provision of 49 and the metal trace 145 is only 2 mils.

FIG. 18 shows a second embodiment of a photodetector with two rectangular active areas and bonding pads directly on each active area. In this example,
Two active areas are created on the substrate 151. The first active area 152 is rectangular. The first active area 152 is made by appropriately doping a rectangular area.
A rectangular dead zone 153 is created around this first active area 152. The rectangular second active area 154 completely surrounds the first active area 152 and the dead zone 153. The second active area 154 is made by suitable doping of the outer rectangular ring. The dead zone 153 separates the active area 152 and the active area 154 to electrically isolate them. The common lead wire 158 is attached to the substrate via the bonding pad 157. Each active area 152, 154 constitutes a photodiode with the underlying substrate.

FIG. 18 shows a second connection type for the active area. In this embodiment, bonding pads are provided directly on each active area. The metal lead wire 155 supplies current to the first active area 152 through the bonding pad. Similarly, the second metal lead 156 supplies current to the second active area 154 via the bonding pad. In each active area, a portion of the active area is sacrificed to form the bonding pad. Also, the metal lead 155 will cast a shadow over the second active area 154, as shown in FIG.

The improved photodetector of FIGS. 15-18 has been described above primarily for a preferred embodiment of the type in which the active area forms a photodiode on the substrate, but with a different type of active area. A photo detection element may be used. For example, it is conceivable to construct the photodetector by areas within a two-dimensional charge coupled device (CCD) array. In that case, the central active area can consist of a large number of light-sensitive pixels (eg, a 2 × 2 square sub-array) of a CCD array. The peripheral active area may consist of a number of light sensitive pixels around the central active area (eg, a two pixel wide ring around the square central active area). The signal from the central active area can be produced by shifting out the charge value of each pixel in the 2 × 2 square sub-array and averaging the charge values over the number of pixels in the central active area. The signals from the surrounding active areas can be made in a similar way. Alternatively, the sum signal can be made directly by averaging the charge values together over the two zones.

FIG. 19 shows that the decoder 47 has two different resolutions.
7 is a flowchart showing a process of obtaining one correct decoding result from one data stream. First step ST1
Then, the decoder 47 simultaneously reads the data from the two channels. Hereinafter, the data from the two channels will be referred to as data A and data B. Arbitrarily
One of the two data inputs corresponds to the low resolution data stream and the other corresponds to the high resolution data stream. In step ST2, the decoder attempts to decode the data A. In step ST3, the decoder determines whether the attempt to decode the data A was successful. If successful, the process proceeds to step ST8, emits a beep indicating a successful scan, followed by step ST9.
Then, the decrypted data is output, and the program ends in step ST10. However, if it is determined in step ST3 that the attempt to decode data A is unsuccessful, then in step ST4, the decoder attempts to decode data B. Next, in step ST5, the decoder determines whether the attempt to decode data B was successful. If it is successful, the process proceeds to step ST8 again, and after instructing the successful scanning, the decoded data is output in step ST9, and the program ends in step ST10. However, if in step ST5 it is found that the attempt to decode the data B is unsuccessful, the decoder executes the scan merge algorithm in step ST6.

Next, the scan merge algorithm will be described with reference to FIG. As shown, channel # 1 is
A pulse signal containing one error is generated from the digitizer. However, for a particular bar code standard, some parts of the signal indicate that the data is within acceptable limits. Similarly, channel # 2 produces a pulsed signal with one error from its digitizer, with some portion of the signal indicating that the data is within tolerance. The position of the error included in the data of channel # 1 is different from the position of the error included in the data of channel # 2. The microprocessor decoder identifies which portion of the data from each channel is within acceptable parameters. The microprocessor decoder discards the erroneous data from the two channels and combines the allowed portions of the data from the two channels to produce one correct final read result (modified signal in Figure 20). Thus, even if two channels produce data that cannot be decoded successfully, the microprocessor decoder can merge the data from the two channels to produce one correct result.

The scan merge algorithm is described in US Pat.
Similar to the process disclosed in No. 07 / (Title of Invention; Method and Apparatus for Decoding Bar Codes from Multiple Scans). The U.S. patent application describes analyzing scan signals to determine correct data, decoding and merging data from a series of scans. The scan merging algorithm in this case is similar, but suitable for processing scan data received simultaneously from two different resolution channels.

Returning to FIG. 19, after executing the scan merge algorithm in step ST6, the decoder determines whether the scan merge was successful. If it is successful, the process goes to step ST8 again to instruct the success of scanning, and then at step ST9, after outputting the decoded data, at step ST10, the program ends. If the scan merge cannot obtain the correct decoding result, the program cannot output the correct decoded data and ST10
Ends with.

The above description of the software is simplified and limited because it concentrates on processing the data from the two channels to obtain the decoding result. The decoder may further include automatic identification of the different code symbols and may be equipped with suitable software to find the actual code data in the analog scan signal containing the pulses representing the light reflected from another target. ..

The microprocessor decoder can also be programmed with functions relating to the operation of the integrated terminal. A terminal device generally has a considerable amount of memory,
It could have a keyboard, a display, and some kind of data interface for communication. In such an integrated terminal, the microprocessor
Responsive to keyboard input of data or instructions, display scanned or keyed data, and control data transfer to an external data processing device.

The present invention has been basically described as a two-channel system. It is within the scope of the invention to extend the described embodiments to provide additional data channels with even different resolutions.

[Brief description of drawings]

FIG. 1 is a perspective view of a wand bar code reader during bar code scanning incorporating the present invention.

2 is a diagram showing two effective detection spots for various working angles of the wand shown in FIG. 1. FIG.

FIG. 3 shows two effective detection spots of the present invention passing over a relatively dense bar code symbol.

FIG. 4 shows two valid detection spots passing over one bar element of a low density dot matrix bar code symbol.

FIG. 5 is a block circuit diagram of a first embodiment of the present invention using digitizers of different resolutions.

FIG. 6 is a diagram showing a high-resolution bar code and signals generated in the circuit of FIG. 5 by scanning the bar code.

7 is a diagram showing a noisy bar code printed by a dot matrix printer and signals generated in the circuit of FIG. 5 by scanning the bar code.

FIG. 8 is a block circuit diagram of a second embodiment of the present invention using two light emitters and two photodetectors.

FIG. 9 is a block circuit diagram of a third embodiment of the present invention using two light emitters, one photodetector and a multiplexer.

FIG. 10 is a cross-sectional view of the optical detection device of the present invention.

11 is a cross-sectional view taken along the line CC of FIG.

12 is a cross-sectional view taken along the line AA of FIG.

13 is a cross-sectional view taken along the line BB of FIG.

FIG. 14 is a cross-sectional view of an optical detection device of the present invention similar to FIG. 5, showing light rays emitted by an LED illuminating a bar code symbol.

FIG. 15 is a schematic plan view of a photodetector having two active areas, one active area surrounding the other active area.

16 is a block circuit diagram of a fourth embodiment of the present invention using one light emitter and two active areas shown in FIG.

FIG. 17 is a detailed view of the photodetector of FIG. 5, showing two circular active areas and a scheme for connecting to the central active area through an insulating passage that traverses the surrounding active areas.

FIG. 18 shows the light of FIG. 15 showing two rectangular active areas, a bonding pad on the central active area, and another method of connecting to the central active area with leads that span the surrounding active areas. It is a detailed view of a detector.

FIG. 19 is a flowchart showing the process by which the decoder derives one correct result from two data streams of different resolutions.

FIG. 20 is an enlarged view showing a bar code symbol, a signal obtained from two channels, and a signal corrected by a scan merge algorithm.

21 is a cross-sectional view of an alternative optical detection device used in the embodiment of FIG.

22 is a cross-sectional view of the second embodiment of the optical detection device taken along the line DD of FIG.

23 is a diagram showing spherical aberration and focal length of a lens used in the optical detection device of FIG.

[Explanation of symbols]

 S1, S2 Two effective detection spots with different diameters T1, T2 Threshold L1, L2 Lens T.S. SA Lateral spherical aberration L.L. SA longitudinal spherical aberration 10 wand type bar code reader 20 bar code 23 bar element of dot matrix type bar code 41 LED 42 PD 43,44 signal adjusting circuit 45,46 digitizer 47 decoder 51 first LED 52 first PD 53 signal adjusting circuit 54 1st digitizer 55 2nd LED 56 2nd PD 57 Signal adjustment circuit 58 2nd digitizer 61 1st LED 62 2nd LED 63 PD 64,65 Multiplexer 66,67 S / H circuit 68,69 Signal adjustment circuit 70 1st digitizer 71 2nd Digitizer 72 Clock 75 Device housing 77 Optical element (axicon 1 and axicon 2) 79 Sleeve 131 LED 132 Adder 133 Signal conditioning circuit 134 1st digitizer 137 Signal conditioning circuit 138 Digitizer 141 Substrate 142 First active area 143 Dead zone 144 Second active area 145146 Metal trace 147 Bonding pad 148 Lead wire 149 Narrow inactive area 151 Substrate 152 First active area 153 Dead zone 154 Second active area 155, 156 Lead wire 157 Bonding pad 158 Lead wire

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor David P. Gorlen, New York, USA 11779 Ronkonkoma Victory Drive 245 (72) Inventor, Joseph Katz, New York, USA 11790 Stony Brook Harlock Meado Drive South 12 (72) Inventor, Yayun Lee United States New York 11742 Holtsville Storm Drive 279 (72) Inventor Jerome Swats United States New York 11733 Oldfield Crane Neck Road 19 (72) Inventor Thomas Mads New York 11746 Huntington Station Long Street 8

Claims (47)

[Claims] 1. A method for expanding the range of the working angle of a wand reader when reading optically encoded information, wherein the working angle is the main axis of the wand reader and the optically encoded information. Defined as an angle formed by a line perpendicular to the surface), (a) (i) optically sensing the light reflected from the first effective detection spot of the first diameter, and (ii) from the first diameter Arranging a light emitting element and a detection element in the wand to optically sense light reflected from a second effective detection spot of a large second diameter, (b) optically detecting the first and second effective detection spots. By passing the encoded information from one to the other, (i)
Sensing the optically encoded information when the first valid detection spot passes, generating a first detection signal in response, and (ii) sensing the optically encoded information when the second valid detection spot passes. , Correspondingly generating a second detection signal, and (c) deriving a decoded representation of one optical encoded information from the two detection signals, of the first and second effective detection spots. The diameter is increased in proportion to the increase of the working angle, and at various working angles, at least one effective detection spot is a spot of a size suitable for correctly reading the optical coded information. Method. 2. The method of claim 1, further comprising the step of sending the resulting decoded representation of the optical encoded information to a data terminal embedded in the wand. 3. The step of arranging the light emitting element and the detecting element includes the step of emitting a first light to focus and illuminate the first size area, and the second light to emit and focus to the first area. Illuminating a second size area different from the size of the area;
Sensing the light reflected from the two areas,
The method of claim 1, comprising the step of detecting valid detection spots. 4. Arranging the light emitting element and the detecting element comprises emitting light to illuminate an area on the surface of the medium; a first area (first size Sensing light reflected from the second area (having a second size larger than the size of the first area) passing over the optically encoded information, The method of claim 1, comprising the steps of detecting first and second valid detection spots. 5. The step of deriving a decoded representation of the optically encoded information analyzes one of the two detected signals and determines whether the data obtained therefrom represents information within an acceptable parameter range. If the obtained data represents information within the range of permissible parameters, then decoding the data to generate a decoded representation of the optically encoded information, if the obtained data is within the range of permissible parameters. A step of analyzing the other one of the two detection signals to determine if the obtained information represents information within an acceptable parameter, if it represents the outside information, and if the two detection signals If the data obtained from the other one of the data represents information within the range of the permissible parameters, then decoding the data to generate a decoded representation of the optically encoded information. The method of claim 1, wherein 6. If the data obtained from the two detection signals represent information outside the range of the permissible parameters, the step of obtaining the decoded representation comprises analyzing one of the two detection signals, Identifying and decoding all parts representing information within an acceptable parameter, analyzing another one of said two detection signals to identify all parts representing information within an acceptable parameter. 6. Decoding, and combining the identified and decoded portions of the two detected signals to produce a decoded representation of one optical encoded information. the method of. 7. A wand type reader capable of reading optical coded information over a wide range of working angles (wherein the working angle is the main axis of the wand type reader and the optical coded information. Defined as an angle formed by a line perpendicular to the surface), (a) (i) disposed in the wand so as to optically sense the light reflected from the first effective detection spot of the first diameter, When the first effective detection spot passes, it senses the optical coded information and generates a first detection signal in response, (ii) light reflected from a second effective detection spot having a second diameter larger than the first diameter. A light-emitting element and a detection element, which are arranged in the wand so as to optically sense the optical coding information, sense the optically encoded information when the second effective detection spot passes, and generate the second detection signal accordingly; ) One from two detection signals Means for deriving a decoded representation of the optically encoded information, the diameters of said first and second effective sensing spots increasing in proportion to the increase of the working angle, and at various working angles at least one The reading device, wherein the effective detection spot is a spot of an appropriate size for correctly reading the optical coded information. 8. A data terminal device embedded in the wand, the data terminal device receiving a decoded representation of the optical encoded information from the means for deriving the decoded representation. 7. The method according to 7. 9. A method of reading optically encoded information, the method comprising: exposing the optically encoded information; sensing light reflected from the optically encoded information to obtain different resolutions for the optically encoded information. Generating two data streams with, and two with different resolutions
Deriving a decoded representation of one optically encoded information from one data stream. 10. The step of sensing light reflected from the optically encoded information comprises: (i) digitizing a signal generated by sensing the reflected light using a first digitizer threshold level. And (ii) digitizing the signal generated by sensing the reflected light using a second digitizer threshold level different from the first digitizer threshold level, wherein the optical code or information The steps to derive the decoded representation are
A method according to claim 9, characterized in that it is responsive to the results of steps (i) and (ii). 11. The exposing step comprises the steps of (i) emitting a first beam of light to focus and illuminate an area of a first size, and (ii) emitting a second beam of light to focus. Irradiating an area having a second size different from the size of one area, and (iii) passing the two irradiation areas from end to end of the optical coded information, wherein the optical coded information 10. The step of sensing light reflected from the two areas separately senses light reflected from the two areas as they pass through the optical encoded information. The method described in. 12. The step of sensing light reflected from the optically encoded information includes sensing light reflected from a first area (having a first size) that passes over the optically encoded information. And sensing light reflected from a second area (having a second size different than the size of the first area) that has passed over the optically encoded information. Item 9. The method according to Item 9. 13. The step of deriving a decoded representation of the optically encoded information analyzes one of the two data streams to determine if the data therein represents information within acceptable parameters. Decoding the one of the data streams to produce a decoded representation of the optical coded information if the analyzed data represents information within an acceptable parameter range, if the analyzed data If represents information outside the range of acceptable parameters, then analyzing the other one of the two data streams to determine whether the data therein represents information within the range of acceptable parameters, And if the data analyzed from the other one of the data streams represents information within the allowed parameters, recover the other one of the data streams. And generating a decoded representation of the optically encoded information. 14. If the data analyzed from the two data streams represent information outside the range of acceptable parameters, the step of deriving a decoded representation of the optical coded information may include extracting one of the data streams. Analyzing and identifying and decoding all parts representing information within the acceptable parameter range, analyzing another one of the data streams to identify all parts representing information within the acceptable parameter range. 14. The steps of identifying and decoding, and combining the identified and decoded portions of the two data streams to produce a decoded representation of one optical encoded information. The method described in. 15. A device for reading optically encoded information, the detecting means optically sensing the optically encoded information and generating at least one electrical signal corresponding to the optically encoded information in response thereto. Responsive to the at least one electrical signal, means for directing two data channels for each scan or each pass of the optically encoded information by the detection means, the two data channels having different resolutions. And
The resolution of one data channel is higher than the resolution of the other data channel), and a decoder responsive to the derived two data channels to produce one data output representing optically encoded information. A device characterized by being present. 16. The detecting means includes: at least one light source that emits light for reflecting the optically encoded information; and, at least one electrical signal that detects the reflected light and that corresponds to the detected reflected light. Device according to claim 15, characterized in that it comprises at least one detector. 17. The means for directing two data channels comprises two digitizers.
5. The device according to item 5. 18. The apparatus of claim 17, wherein the two digitizers both respond to the same electrical signal but each have different threshold levels that define two different resolutions. 19. The apparatus of claim 16, wherein the at least one light source comprises a single light source. 20. The apparatus of claim 19, wherein the at least one detector comprises a single detector. 21. The apparatus according to claim 20, wherein the means for guiding the two data channels comprises two digitizers. 22. The two digitizers are both responsive to a single electrical signal from the single detector, and the two digitizers each have different threshold levels that define two different resolutions. The device of claim 21, wherein the device is characterized. 23. The apparatus of claim 16, wherein the at least one detector comprises a single detector. 24. The at least one light source comprises a first light source and a second light source, and the first detector allows the reflected light emitted from each light source to be separately detected by the single detector.
16. Device according to claim 15, characterized in that the operations of the second light source are multiplexed. 25. The apparatus of claim 15, wherein the first and second light sources illuminate different areas. 26. The apparatus of claim 16, wherein the at least one light source comprises two light sources. 27. The device of claim 26, wherein the at least one detector comprises two detectors. 28. The apparatus of claim 16, wherein the at least one detector comprises two detectors. 29. The at least one detector comprises a first active light detection area formed on a substrate and a second active light detection area formed on the substrate around the first light detection area. 16. The device of claim 15, comprising: 30. The device of claim 29, wherein the second active light detection area substantially surrounds the first active light detection area. 31. The device of claim 30, wherein the first active light detection area is centrally located inside the second active light detection area. 32. The device of claim 29, wherein the first active light detection area and the second active light detection area each comprise a photodiode. 33. Means for directing two data channels is means for digitizing a signal obtained from a first active photodetection area to create a high resolution data channel, and a signal obtained from a second active photodetection area and a second. 30. Apparatus according to claim 29, comprising means for summing the signals obtained from the active light detection area and means for digitizing the output of said summing means to produce a low resolution data channel. 34. The apparatus of claim 15, wherein the optically encoded information comprises bar code data, and the decoder comprises means for decoding the bar code data. 35. The apparatus of claim 16, further comprising a wand type housing, wherein the at least one light source and the at least one detector are contained within the housing. 36. The device of claim 35, further comprising an integrated data terminal device including a keyboard and a display, wherein elements of the integrated data terminal device are contained within the housing. 37. A first light emitting element which emits light along a first optical axis, a second light emitting element which emits light along a second optical axis parallel to the first optical axis, And a light detection element for receiving and detecting light emitted from the second light emitting element and reflected along a third optical axis parallel to the first and second optical axes, a first light emitting element along the first optical axis A first half axicon optical element for determining the depth of field and the spot size of the light emitted by the first light emitting element and received by the light detecting element, and the second light emitting element along the second optical axis. And has at least one optical property different from that of the first half axicon optical element, the second light emitting element emits light, and the light detecting element receives the depth of field and the spot size (first About the light emitted by the light emitting element and received by the light detecting element Apparatus according to claim 15, characterized in that it consists of an optical detection device including a second half-axicon optical element, which define different) from the depth of field and spot size. 38. The detecting means comprises a first light emitting element which emits light along a first optical axis, a second light emitting element which emits light along a second optical axis parallel to the first optical axis, (i) A first active photodetection area formed on the substrate, (i
i) A third active light detection area formed on the substrate around the first light detection area, and a third active light detection area which is parallel to the first and second optical axes and which exits from the first and second light emitting elements. A light detecting element for receiving and detecting light reflected along the optical axis, a first half-axicon optical element aligned with the first light emitting element along the first optical axis, and a second optical axis 16. The apparatus of claim 15 comprising a second half axicon optical element aligned with the second light emitting element. 39. A first light emitting element emitting light along a first optical axis, a second light emitting element emitting light along a second optical axis parallel to the first optical axis, first and second light emitting elements. A photodetector element for receiving and detecting light reflected from a third optical axis parallel to the first and second optical axes and aligned with the first light emitting element along the first optical axis. A first half axicon optical element that determines a depth of field and a spot size for light emitted by the first light emitting element and received by the light detection element, and aligned with the second light emitting element along the second optical axis, It has at least one optical property different from that of the first half axicon optical element, and the depth of field and the spot size (light emitted from the first light emitting element from the second light emitting element and received by the photodetector element) For the light received by the detector, the depth of field and spot The optical detection device comprising a second half-axicon optical element, which define different) from the size. 40. The optical property is an angle α of each half axicon optical element, and α of the first half axicon optical element is different from α of the second half axicon optical element. Item 39. The photodetector according to Item 39. 41. The photodetector according to claim 39, wherein the first and second light emitting elements are light emitting diodes. 42. The photo-detecting device according to claim 39, wherein the photo-detecting element is a photodiode. 43. The photodetection element comprises a first active photodetection area formed on a substrate and a second active photodetection area formed on the substrate around the first photodetection area. 4. The method according to claim 3, wherein
9. The photodetector according to item 9. 44. A multi-channel photodetector comprising: a first active light detection area formed on a substrate; and a second active light detection area formed on the substrate around the first light detection area. 45. The multi-channel photodetector of claim 44, wherein the second photodetection area substantially surrounds the first photodetection area. 46. The multi-channel photodetector according to claim 45, wherein the first photodetection area is centrally disposed inside the second photodetection area. 47. The multi-channel photodetector of claim 44, wherein each of the first and second photodetection areas comprises a photodiode.